Digital Cameras - Olympus C-2500L Test Images

(Original test posting: 11/7/99)

We've begun including links in our reviews to a Thumber-generated
index page for our test shots. The Thumber data includes a host of
information on the images, including shutter speed, ISO setting, compression
setting, etc. Rather than clutter the page below with *all* that detail,
we're posting the Thumber index so only those interested in the information
need wade through it! ;)

Outdoor portrait:(1556k) Exceptional color handling: The blues of the
flowers in this shot are a frequent problem for digicams we test: Many tend
to put too much red into them, rendering them as a purplish hue. The C-2500L
gets them just right, and at the same time produced a much purer hue in
the yellow flower than we're accustomed to seeing. The flesh tones are also
spot-on, again among the best we've seen (October 1999). This shot also
shows the C-2500's love of contrast though: The highlights in the model's
shirt are pretty "hot" here, and the highlights on her face are
quite strong as well. As noted below in our analysis of the "Davebox"
image, you'll do well with the C-2500 to use soft lighting whenever possible,
and in high-contrast conditions, to expose for the highlights, and rely
on the camera's excellent shadow detail to hold the information you need
in the shadows. (This is always good advice with a digicam, but the C-2500L
has higher contrast than most, making it doubly applicable.)

We felt the Auto white balance was most accurate here, but include this
shot taken with the 5500K white balance(1538k)
as a comparison for those interested. The 2500's exposure system did a pretty
good job on this difficult subject, only requiring a 1/3 EV boost for our
main shot. (1556k) The
table below shows the results of a range of exposure compensation, from
0 to +1.2 EV.

Closer portrait:(1597k) As usual, this shot requires less exposure
compensation than the test above, because the model's face fills more of
the frame. We chose as our main shot(1597k)
the one with no exposure compensation at all. Again, excellent color and
tone, and particularly good skin tones, although again with rather high
contrast. Good detail, and excellent shadow detail. We're not sure why (a
settings confusion?), but the overall tone of the 0EV-compensated
version(1597k) is somewhat warmer than the +0.9EV
image(1570k). This was the only shot we saw this
effect in, so it may have just been a confusion as to the white balance
setting we used. As above, the table below shows the results of exposure
compensation settings ranging from 0 to +1.2EV.

House shot:(1846k) Always a tough test of camera resolution,
the C-2500L did exceptionally well on this test, with arguably the best
detail rendition of any camera to date. (October, 1999) Color was also exceptionally
accurate in the Auto white balance mode.

This shot also provided a good test case for comparing the in-camera sharpening
to what you can achieve with Photoshop(tm) on the "soft" version
of the file. First and foremost, the C-2500L's built-in sharpening is very
much on a par with what we've seen in other digicams, not at all bad, IOHO.
Still, the unsharp masking operator in Photoshop does a fair bit better
when applied to the "soft" (unsharpened) image, bringing out not
only exceptional detail in the tree branches, but wonderful texture in the
bricks as well. (Try a setting of 0.5 pixels, 125% on this
shot.(1905k)) Overall an extraordinary performance.

Note: This link (7,047K!) is to
an uncompressed TIFF version of this image. Your browser most likely won't
know what to do with it. Download the file to your computer and open in
an image-editing program to inspect it.

Far-Field shot:(933k) This image is shot at infinity to test far-field
lens performance. NOTE that this image cannot be directly compared to the
other "house" shot, which is a poster, shot in the studio. The
rendering of detail in the poster will be very different than in this shot,
and color values (and even the presence or absence of leaves on the trees!)
will vary in this subject as the seasons progress. In general though, you
can evaluate detail in the bricks, shingles, and window detail, and in the
tree branches against the sky. Compression artifacts are most likely to
show in the trim along the edge of the roof, in the bricks, or in the relatively
"flat" areas in the windows.

Wow! This shot makes it official: The C-2500L takes the crown for image
detail, at least as of the writing of this review (October, 1999)! There's
detail in the branches against the sky that just isn't evident in shots
we've taken previously with other cameras. The effect of applying unsharp
masking in Photoshop to the images shot in "soft" mode is particularly
impressive here. (Try 150% at 0.6 pixels on the highest-resolution "soft"
version of the image below, to see what we're talking about.)

The camera did completely lose the highlight detail in the white trim around
the bay window in the center of the house, but there were several extenuating
circumstances: 1) The house was recently repainted, and the new paint is
both a brighter white to begin with, and minus 4 years of accumulated mildew
(this is in Atlanta. 2) We shot this image before we'd closely examined
some of the other shots, and so weren't prepared for the contrast factor.
- To make matters worse, we also boosted exposure by 1/3 EV, to compensate
for the overall darkening the camera's exposure system was trying to do,
due to the bright white paint. 3) Shot in late October, the sun is unavoidably
hitting this south-facing wall much more directly than it does in the summertime,
when many of the other shots on this site were taken. - Not to completely
excuse the camera for losing the highlights, but the cards really were stacked
against it in this test. (Time permitting, we'll try to reshoot, with the
exposure dialed-down somewhat.)

With all the hubbub on the internet recently over the in-camera vs. post-exposure
sharpening issue, we've decided to include a FULL series of shots here,
taken in both "normal" and "soft" modes. The tables
below contain links to sample images captured in all resolution modes, at
all ISO values (to evaluate noise behavior as a function of ISO), and in
both normal and soft sharpness modes...Resolution/Quality Series, Normal sharpness setting:

Note: This l ink (7,047K!) is
to an uncompressed TIFF version of this image. Your browser most likely
won't know what to do with it. Download the file to your computer and open
in an image-editing program to inspect it.ISO Series, Normal sharpness setting:

Note: This link (7,047K!) is to
an uncompressed TIFF version of this image. Your browser most likely won't
know what to do with it. Download the file to your computer and open in
an image-editing program to inspect it.ISO Series, Soft sharpness setting:

Lens Range (new): We've received
a number of requests from readers to take shots showing the lens focal length
range of those cameras with zoom lenses. Thus, we're happy to present you
here with the following set of shots, showing the field of view with all
the lens options Olympus currently (October, 1999) offers for the C-2500L.
Note that both images here are shot in 1280x1024 pixel mode, to ease download
times.

Wide, w/0.85x conversion lens
(388k)

Wide
(384k)

Telephoto
(398k)

Telephoto, w/1.45x conversion lens
(403k)

"Musicians"
poster:(1838k) The C-2500L's performance
on this shot was pretty consistent with it's handling of the other tests.
Resolution is exceptionally high, as evidenced by the clearly-resolved fine
silver threads in the oriental model's kimono. Colors are very accurate,
although the higher contrast here has reduced the saturation of brighter
colors somewhat, such as the yellows in the black model's costume. The table
below contains samples of all resolution and quality settings, shot with
automatic white balance, and normal sharpness. Here's an example shot in
"super high quality" mode, with the sharpness
option set to Soft(1777k).Resolution/Quality Series, Soft sharpness setting:

Note: This link (7,047K!) is to
an uncompressed TIFF version of this image. Your browser most likely won't
know what to do with it. Download the file to your computer and open in
an image-editing program to inspect it.

Macro shot:(1694k) The C-2500L has both a normal macro mode,
which lets it focus down to about 12 inches, and a "Super Macro"
mode, that gets it down to as close as 0.8 inches, albeit only with the
lens set to its widest-angle position. Here are shots taken with standard
macro(1694k) and super
macro(???k) modes, as well as a standard macro
with flash(1679k) shot. Super macro clearly gets
into the "microscopic" realm, albeit at some cost in terms of
severe geometric (principally barrel) distortion. The Olympus "Camedia
Master" software includes a filter for correcting geometric distortion,
which works very well with the normal lens operating modes, and does a fair
job of correcting the Super Macro distortion. This
picture(563k) shows the maximum correction for
barrel distortion applied in Camedia Master.

Minimum coverage area in standard macro mode is 3.54 x 4.43 inches (9.0
x 11.25 mm), while Super Macro takes you down to a minimum area of only
1.48 x 1.85 inches (3.8 x 4.7 mm).

"Davebox"
test target:(1759k) In this test, the automatic
white balance option won out by just a hair, producing slightly more neutral
whites and grays than the preset white balance option. The 5500K preset
white balance (which should correspond with "standard daylight"
produced a very slightly yellowish cast.

We examined this image first among our test images for this camera, wanting
to really understand the details of what the C-2500L does with color and
tonality. What we found was very impressive: The color accuracy overall
is probably the best we've seen on any camera to date (October, 1999). It
not only handles the very difficult red/magenta separation on the horizontal
color chart, but it proved remarkably accurate on the tricky blue and purple
tones of the larger MacBeth(tm) chart. The only weakness we could find,
and it was very slight, was a slightly lower saturation in the bright yellow
swatch. Tonal range in this test was very good, particularly in the shadows:
Comparing the C-2500L's version of this shot to others we've taken with
other 2 megapixel cameras, we found significantly more shadow detail in
the black chunks of charcoal in the image from the '2500. Highlight detail
is good also, but the highlights in this scene aren't nearly as strong as
those in the Outdoor Portrait shot above. We observed a slight tendency
for the very bright specular highlights in the pot lid to "bloom"
in the blue and red channels. The amount in this shot seems about typical
of other cameras we've tested, but it's been rightly pointed out that these
reflections aren't as strong as those from strobes. (Meaning the effect
could be greater there.) While not one of our standard tests, we tried shooting
both the pot lid itself and a piece of crumpled aluminum foil, with the
on-board strobe enabled, and even boosted the strobe's output by +2 EV to
maximize any effect. Interestingly, we felt the blooming was less evident
under these severe conditions than under our normal studio lights. (No conclusion
to be drawn from this rather unscientific test, other than that blooming
doesn't appear to be more of a problem with the C-2500L than with other
cameras we've tested.)

Prior to reviewing C-2500L, we'd heard some comment on the internet regarding
image noise relative to competing units, particularly when its in-camera
sharpening algorithm is allowed to work. Because of this, we especially
scrutinized the image noise in the various swatches of the MacBeth(tm) chart,
and compared it visually to other 2 megapixel-plus cameras. What we found
was interesting: Image noise in the 2500 appeared to be significantly less
in absolute magnitude, but was more sharply defined than in other cameras.
(Small, tight speckles, rather than large, diffuse blurs.) We suspect that
this results in it being more apparent in some images, even though it is
of a lower amplitude on an absolute basis. Readers particularly interested
in digicam image noise can download "Davebox" test images from
several cameras, and examine the individual color channels in Photoshop(tm).
- In the original, the swatches in the MacBeth(tm) target are extremely
"flat" and uniform in tone, and so make a good basis for evaluating
noise. From our testing, we believe that the C-2500L can produce "cleaner"
images than those from other cameras, but you'll probably want to capture
shots in "soft" mode and use an image-manipulation program like
Photoshop for sharpening to get the most out of your images.

As noted, we chose the Auto white balance setting for our main
shot(1759k) here, but also include the following
images for your perusal, taken using the preset white(149k), and 5500K (146k)white
balance settings. All the shots in the table below were taken with the
"normal" sharpness setting, here's a large/high-quality version
taken using the "soft" setting(1850k).Resolution/Quality Series, Soft sharpness setting:

Note: This link (7,047K!) is to
an uncompressed TIFF version of this image. Your browser most likely won't
know what to do with it. Download the file to your computer and open in
an image-editing program to inspect it.

Low-Light Tests
We found that the C-2500L worked quite well under low-light conditions,
producing high-quality images down to a light level of about 1 foot-candle
(11 lux). Below that level, noise increased significantly, and we really
didn't get any usable images at light levels less than about 0.5 foot-candles
(5.5 lux). Given the ability to boost the ISO to 400, the relatively fast
f/2.8 lens, and exposure times ranging out to 8 seconds, we were a bit surprised
we couldn't go lower than this level. We discovered though, that Olympus
limits the maximum exposure time to only 2 seconds when the ISO is boosted
to 400, apparently to prevent people from taking images with more noise
in them than the Oly engineers find acceptable.(!) On the other hand, the
images at 1 foot-candle were exceptionally clean, with excellent color rendition,
frequently a problem in digicams we've tested at that low a light level.
(For reference, 1 foot-candle is about the level of lighting in our "unscientific"
outdoor night shot shown below, that we sometimes shoot with promising cameras.)
Thus, the C-2500L should work very well for shooting night scenes under
typical street lighting, at outdoor (or indoor) restaurants, etc.

The table below shows the results we obtained in the studio, under a range
of illuminations, from 8 foot-candles (88 lux) down to 0.5 foot-candles
(5.5 lux). All images were shot at ISO 100, except the second 0.5 foot-candle
sample, captured at ISO 400.

"Real" shooting conditions: Scientific laboratory measurements
are fine, but how does the camera do in "real life"? Quite well,
thanks. Here is a series of shots taken at the local mall/movie complex.
Illumination is about 1 foot-candle (11 lux), from a mix of high-pressure
sodium, mercury vapor, and incandescent lighting. We shot one picture at
each of the preset ISO values, although we really mis-interpreted what we
were seeing on the LCD, with the result that we overexposed all but the
ISO 100 version. (A word to the wise: You can't always trust the LCD to
gauge exposure by!) Still, this gives you some idea of what the camera can
do in a "real life" low-light setting. We also took a shot with
the white balance set to 3000K, matching the indoor lighting better, and
giving the outdoor lighting a bit cooler hue.

ISO 100
Shutter: 1/ 2
Aperture: F2.8
(1681k)

ISO 200
Shutter: 1/ 2
Aperture: F2.8
(1678k)

ISO 400
Shutter: 1/ 2
Aperture: F2.8
(1861k)

ISO 400, 3000K white balance
Shutter: 1/ 2
Aperture: F2.8
(1834k)

Flash Range Test
(This test was added in August 1999, so cameras tested before that time
won't have comparison pictures available. As we go forward though, all the
new models will have similar tests available.) Olympus specifies a maximum
flash range for the C-2500L's onboard strobe of 8.2 feet in telephoto mode
(the lens setting with the smallest aperture), and at an ISO setting of
100. In our own tests, we really felt that the flash worked quite well out
to 10 feet or more, and even the shot taken at 14 feet (C25FL141.HTM) was
still reasonably bright. Of course, boosting the ISO rating also increases
the flash range, and the increase from ISO 100 to 400 should roughly double
the range of the flash. This would take it out to 16 feet (5 meters) according
to Olympus' official rating, and perhaps 20 feet or more, based on our own
tests.

Then, there's the optional add-on flash unit, the FL-40. Not only is the
FL-40 a much more powerful strobe unit, but it's head incorporates an optical
zoom mechanism that concentrates the light into a narrower beam when the
camera lens is zoomed to a telephoto setting. This greatly extends the range
of the flash, giving a "official" range of 10 meters (about 33
feet) with an ISO setting of 100, and up to 20 meters with a setting of
400. Finally, you can combine the onboard flash with the FL-40, to get even
greater range. We don't have any formal tests to show it, but we entertained
ourselves by taking strobe pictures of a neighbor's yard about a hundred
feet away in pitch blackness, with the camera set to ISO 400, and both flash
units working together. Very impressive! ('Not sure how the neighbors felt
about all this midnight strobe activity - hopefully they were asleep...)

The table below shows the results we obtained with the C-2500L's onboard
flash, at distances ranging from 8 to 14 feet. (All shots were taken at
ISO 100 unless otherwise indicated.)

ISO 12233 ("WG-18")
resolution target:(1585k) In keeping with
its high-resolution 2.5 megapixel sensor, the C-2500L turned in the highest
marks to date (October, 1999) on the resolution test target. We observed
a visual resolution of 700-750 lines per picture height in the vertical
direction, and easily 800 lines or more in the horizontal. What's more,
when the inevitable aliasing occurs at higher frequencies, it's very well
controlled and unobtrusive. Overall, an exceptionally impressive performance!
In the tables below, we've included a full resolution/quality series for
both wide and telephoto, as well as links to targets shot in the "soft"
mode (without in-camera sharpening) at the wide-angle zoom setting.Resolution/Quality Series, Wide Angle, "Normal"
sharpness:

Note: This link (7,047K!) is to
an uncompressed TIFF version of this image. Your browser most likely won't
know what to do with it. Download the file to your computer and open in
an image-editing program to inspect it.Resolution/Quality Series, Wide Angle, "Soft"
sharpness:

Note: This link (7,047K!) is to
an uncompressed TIFF version of this image. Your browser most likely won't
know what to do with it. Download the file to your computer and open in
an image-editing program to inspect it.Resolution/Quality Series, Telephoto, "Normal"
sharpness:

Note: This link (7,047K!) is to
an uncompressed TIFF version of this image. Your browser most likely won't
know what to do with it. Download the file to your computer and open in
an image-editing program to inspect it.

Viewfinder accuracy/flash uniformity target:
Like Olympus' other SLR (single-lens reflex) digicams, the C-2500L doesn't
provide an option to use the LCD panel as a viewfinder. The optical viewfinder
is quite accurate though, showing almost exactly 95% of the final image
area at both wide angle(532k)
and telephoto(547k) lens
settings. We'd still like the option of using the LCD as a viewfinder, preferably
to get all the way to 100% accuracy, but the accuracy of the TTL (through
the lens) optical finder is quite good.

We now routinely measure lens distortion as part of our camera testing.
The C-2500L showed moderate geometric distortion at both ends of the lens'
zoom range, with 1.3% barrel distortion at the wide angle end, and 0.64%
pincushion distortion at the telephoto setting. In the main review, we mentioned
Olympus unique provision of a "distortion" filter in their Camedia
Master software for dealing with these distortions: We doubt we'll see always-perfect
lenses on digicams any time soon, but can see no reason why other manufacturers
shouldn't include such processing in the software for their cameras. (Our
only complaint is that it should be possible to batch-apply this correction
to more than one image at a time.) At least in our viewfinder accuracy test
pictures, the correction was perfect, as seen here in corrected versions
of the wide angle(280k)
and telephoto(294k) shots.

The C-2500L's lens shows slight chromatic aberration at the wide angle end
of its range, roughly 1 pixel's worth, or 0.06%, while at the telephoto
end, it shows none at all.

Chromatic aberration was almost non-existent at both telephoto and wide
angle lens settings. (At the wide angle end, there's slight flare in the
blue channel that could be mistaken for chromatic aberration, but even this
is very minimal.)